My long-term goal is to understand molecular mechanisms underlying mammalian vascular system development. We are primarily interested in how endothelial-specific receptor tyrosine kinases regulate vascular development. Our proposed studies aim to understand the precise roles of molecules that are involved in the regulation of vascular development. We have gained significant information regarding the roles of many molecules in vascular development in the past years. However, many important questions still need to be addressed. Furthermore, normal functional development of almost all organs depends on vascularization. Therefore, our study of vascular development also contributes to the more complete understanding of the organogenesis in general. Most importantly, the pathogenesis of many human diseases involves new blood vessel formation or regression. Thus, our studies of vascular development will contribute to the invention of unique and effective therapeutic approaches targeted towards many human diseases such as heart failure, stroke, cancer, wound healing, and diabetic retinopathy.